Are my lipos ok?

[Blacksails]

Ok, so on my AD8 HLE I run 2x 5500mAh 5s lipos.
I have two lipo monitors on the back of the bird which give a digital readout of: the full pack voltage and the seperate voltages of each cell.

When flying I tend to land when the monitors are reading 3.6 - 3.7v per cell in a hover. Once i've landed the cell voltage shoots back up a fair amount due to no load. Can I discharge more than this without damaging the cells? I've done some research and there appears to be conflicting views. Some people are saying that 3.7v is the absolute limit, whilst others argue that damage doesn't really start to occur until they've been run down to around 3.3v (under load). Some even say 3.0v.

When I land, my packs are only ever so slightly warm....like almost bearly noticable. Am I playing it too safe? If I can afford to fly for longer without damaging my packs then that would be great!


Also on the topic of lipo care, I know its bad to store a lipo fully discharged/charged but how long is too long? I regularly charge up my packs and leave them a week or two whilst waiting for an opportunity to fly. Is this ok? Or is "storage" classed as leaving them a period of months over the winter?

Cheers for the help

 

[kloner]

more than a week charged at room temp makes damage, not alot but it starts making the internal resistance go up.

if you have a high end charger, they have "special modes" and there is usually an internal resistance test you can do. if not, you really want to get a cell checker that has the IR on it so you know what your using for fuel, and how reliable it is.

Always store your lipos empty, that is the biggest damage aside from over discharging you can do. even in the fridge is better if longer than a week.

I had two lipos die in a weekend while flying, my first clue was the voltage sagged bellow the packs rating pretty fast after takeoff and within seconds of noticing, it was too late. They come down like bricks, lemme tell ya

 

[mailman35]

always store the lipo's empty?
i thought the key was to store them at 50%?
i always take my lipo's down to 20% remaining. and so far so good.

 

[kloner]

you want them around 3.8 to store them. good or not, if you watched ir you'll see it get 2 ohm from leaving them charged to long here, then there then here. next thing you know a new pack that was 4 ohm combigned is reaching into the 20's, then 30's, then hundred, then it runs out earlier than expected and blows out motors, bearings, cameras, etc. it builds and builds till one day shes no more.

the better you treat em the longer and more power, less loss into a pack you'll hit. The question about seeing the cells go so low so early under a load is exactly what it starts doing.